Synthesis, Swelling, and Exfoliation of Microporous Lamellar Titanosilicate AM‐4

Abstract

AM‐4 is a layered porous titanosilicate built from TiO6 and SiO4 polyhedra. An improved synthesis of AM‐4 crystalsenabling control of particle size by secondary growth and reducing synthesis time is presented. A new material, UZAR‐S2, has been obtained by exfoliation of the smaller AM‐4. The exfoliation consists of proton exchange with acetic acid, intercalation with nonylamine, and final activation by washing with HCl/water/ethanol. Besides XRD, TEM, N2 adsorption, FTIR, and UV/Vis characterization highlighting the delaminated character of UZAR‐S2, CO2 adsorption was also measured.

Preparation and characterization of novel chitosan‐based mixed matrix membranes resistant in alkaline media

“…The crystalline domain is completely destroyed after adding the 5 wt % IL. After incorporation of the layered compounds AM‐4 and UZAR‐S3, a band appears at low angles, characteristic of the d ‐spacing between the crystalline nanoporous layers . This band is more remarkable in the latter case, since the exfoliation of the former, AM‐4 titanosilicate, is particularly difficult, and swollen layers are mostly deposited onto CS matrix surface as shown in SEM images [Figure (D)].…”

“…The fillers used for the synthesis of CS‐based MMMs were microporous lamellar titanosilicate AM‐4 (Na 3 (Na, H)TiO 2 (Si 2 O 6 ) 2 ·2H 2 O) synthesized as in Casado et al ., a layered stannosilicate UZAR‐S3 (Na 7 Sn 2 Si 9 O 25 ) . They are composed of Ti and Sn pyramid layers separated by galleries containing Na + cations accounting for high ion‐exchange capacity .…”

“…Thus, the aim of the article is to study the feasibility of novel membrane materials based on green chemistry as alternative materials in electroanalyses, organic electrosyntheses, and fuel cell technology, namely, CS‐based MMMs prepared using several fillers as proof of concept in the MMM approach. These fillers are: layered nanoporous materials prepared without organic surfactants, such as AM‐4 titanosilicate, and novel stannosilicate, UZAR‐S3, with Sn isomorphously substituted in the silicate framework, tin metallic nanoparticles, and 1‐Ethyl‐3‐methylimidazolium acetate ionic liquid (IL) as an example of the effect of the cation–anion tuneability of RTILs as well as the interaction between polysaccharides and ionic liquids as a way to control the rigidity of semicrystalline CS structures . Results and discussion will be provided in terms of the electrochemical characterization by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) to assess the ionic conductivity of the new membranes.…”

Chitosan:poly (vinyl) alcohol composite alkaline membrane incorporating organic ionomers and layered silicate materials into a PEM electrochemical reactor

“…The CS:PVA blend does not reveal changes on the peaks position but the intensity of the peaks is lower than those of pure CS [18] because of the decrease of intermolecular interaction between the polymer blend chains and thus the crystallinity degree is decreased [44]. can thus be attributed to a higher degree of exfoliation [45], probably due to the fact that this layered titanosilicate is dispersed in all the membrane matrix and not only on a top layer. The durability of the solid electrolyte membrane is very important for the commercial application in electrochemical devices.…”

“…Lamellar microporous titanosilicate AM-4 was synthesised by a seeded secondary-growth procedure reported in a previous work [32]. A typical seeded synthesis (to produce about 2.5 g of solid) was as follows: NaOH pellets, distilled water, before the degassing in ultrasound bath, and the mixture was hence stirred for 24 h until homogeneity.…”